Home Brew Forums > Measuring alcoholic content

07-16-2006, 03:28 AM   #1
lovemyholden
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 Measuring alcoholic content

Hello. How do you measure the alchohol content of homebrew? thanks in advance.

07-16-2006, 03:46 AM   #2
apparatus
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1.) Use a hydrometer to measure the original gravity.
2.) Take a hydrometer reading to measure final gravity.
3.) Original gravity minus final gravity multiplied times 131 equals alcohol by volume.
Example: OG 1.050 - FG 1.012 = 38
38 X 131= 4.97 Alcohol by volume.

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07-16-2006, 06:01 AM   #3
david_42
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If you really want to know: purchase a heat-resistant 100 ml graduate cylinder and a good thermometer. Place EXACTLY 100 ml of ale in the cylinder (noting original temperature) and heat in a water bath until the ale reaches 78C. At this point, the alcohol will start to boil off and the temperature will stay at 78C until almost all of the alcohol is gone. When the temperature starts rising again, cool the cylinder to the original ale temperature (so the water shrinks to its original volume). Read the level and subtract from 100. That's your ABV.

If you have a really good scale, you can measure the weight change.
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07-16-2006, 06:03 AM   #4
Muntzster
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Quote:
 Originally Posted by david_42 If you really want to know: purchase a heat-resistant 100 ml graduate cylinder and a good thermometer. Place EXACTLY 100 ml of ale in the cylinder (noting original temperature) and heat in a water bath until the ale reaches 78C. At this point, the alcohol will start to boil off and the temperature will stay at 78C until almost all of the alcohol is gone. When the temperature starts rising again, cool the cylinder to the original ale temperature (so the water shrinks to its original volume). Read the level and subtract from 100. That's your ABV. If you have a really good scale, you can measure the weight change.
Do you actually use that over the hydrometer?

07-16-2006, 06:33 AM   #5
david_42
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No, but it does work.
A. I don't really care about ABV
B. I'm too lazy to do this routinely. I did it on my first cider because the gravity was under 0.990 and I didn't believe it: 8.5% from fresh pressed cider!
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07-16-2006, 08:40 AM   #6
Muntzster
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Quote:
 Originally Posted by david_42 No, but it does work. A. I don't really care about ABV B. I'm too lazy to do this routinely. I did it on my first cider because the gravity was under 0.990 and I didn't believe it: 8.5% from fresh pressed cider!
So i shouldnt waste my money on one ?

07-16-2006, 11:47 AM   #7
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07-16-2006, 01:02 PM   #8
chillHayze
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Quote:
 Originally Posted by Muntzster So i shouldnt waste my money on one ?
The hydrometer method uses an approximation method which is usually on the high side if close at all. david42's method will tell you much more accurately the true content of a particular brew. It will cost 100mL of brew which is not acceptable by some people's standards. :-)

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